Pyridoxal-5'-phosphate is the active form of vitamin B6 and is an essential cofactor for many enzymes, particularly those involved in amino acid metabolism [<cite idref="PUB00053235"/>]. There are three known pathways for pyridoxal-5'-phosphate biosynthesis: the de novo pathway, the salvage pathway, and the fungal type pathway. Bacteria, fungi, parasites and plants all possess at least one of these pathways, but higher organisms, such as insects and mammals, are incapable of synthesising this compound and need vitamin B6 in their diet to survive.Erythronate-4-phosphate dehydrogenase catalyses the first step in the de novo biosynthetic pathway, the oxidation of erythrose-4-phosphate to 4-phosphoerythronate [<cite idref="PUB00053236"/>].